Control of separately-excited generators provided with auxiliary poles.



L. FLEISGHMANN & G. STERN. GONTROL 0F SEPARATELY EXCITED GENERATORS PROVIDED WITH AUXILIARY POLES.

APPLICATION FILED MAR. 11, 1908.

905,508. v Patented Dec. 1,1908.

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UNITED STAT 1 E S AENT OFFICE.

' LIONEL FLEISCHMANN AND Gross STERN. or BERLIN, GERMANY, ASSIGNORS T GENERAL ELECTRIC COMPANY, A CORPORATION on NEW YORK.

CONTROL OF SEPARATELY-EXCITED GENERATORS PROVIDED WITH AUXILIARY POLES.

Specification of Letters Patent.

Patented Dec. 1, 1908.

Application filed March 11, 1908. Serial No. 420,338.

To all whom it may concerm Be it known that we, LIONEL FLniscH- MANN, a citizen of the United States, and GEORG STERN, a subject of the King of Prus- 5 sia, residing at Berlin, Germany, have invented certain new and useful Improvements in the Control of Separately-Excited Generators Provided with Auxiliary Poles,

of which the following is a specification.

Our invention relates to the control of sop arately excited generators provided with auxiliary poles, and has for its object a novel control whereby such generators are pro Ventedif rom building up as series machines.

Separately excited generators provided ,generator from a niaxinuuu to a minimum and then to amaxnnum in the opposite direction, the motor speed is varied from a maximum in one direction to zero. and then to a maximum in the other direction. Even with the generatorfield circuit open, however, the generator produces a voltage due to the residual magnetism in the. main poles which, unless the armature circuit is opened, causes a How of current in the armature. circuit.

magnetic field nearly ninety electrical degrees from its normal position. and the comimitatingpole windings, which are in series with the armature circuit, tend to act as 0 series field windings and make the generator build up as a series i'uachine. This action may be avoided by opening the armature circuit. but in so doing the control system is I complicated. By our invention this building up of a separately excited gent-rater with an aux? iliary field as a series machine is prevented. without necessitating the opening of the armature circuit. This we accomplish by providing means for killing the auxiliary field when the main field circuit of the gen erator is broken.

For a better understanding of our inven- This llow of current displaces the tion and the advantages possessed by it, reference may be had to the following description taken in connection with the accompanyin drawing, in which Figure 1 shows diagrammatically a control system according to our invention, in which the auxiliary field is killed by a short-circuiting switch connected across the terminals of the auxiliary field winding and arranged to be closed when the control .er is in the off position. Fig. 2 shows a modification of ourcontrol system in which the auxiliary field is killed 7 by means or a winding which is excited from the separate exciter in such a direction as to create a magnctoinotive force in the oppositedirection to the auxiliary field. Fig. 3 showsa further modification in which the auxiliary field is killed by means of a winding, the excitation for which is taken from auxiliary brushes on the main generator, and is so directed as to create a field in opposition to the auxiliary field.

In all the figures, A represents the armature of the separately-excited generator with auxiliary field-pole winding (1, and separately-excited' field winding 7). This generator may be driven in any suitable manner.

B represents the separate exciter, which may he a small generator driven by suitable means, or may be a battery.

t represents the armature of-the motor, which is supplied with current from the generator A, and 1: represents the separatelyexcited field of the motor C, which is supplied with constant excitation from the exciter B. i

D represents the :ontrolling switch which is arranged to connect the generator field a to the exciter B to vary the current supplied to the generator field, and in its oli position to actuate ineans for killing or annulliug the auxiliary field, so as to keep the generator from building up as-a series machine.

in the figures. the switch 1) is shown in operative aisitiou for one direction of rotaiiou. In this position it. will he noticed that a circuit is (*OlllPlOl'Ctl from. the exciter B, through the resi mnce l]. the control switch l), contact l. througl'i generator held 6, con tacts and 2, to the other terminal of the exciter. By moving the switch D, more or less of the resistance E is cut into the circuit of the field 5. Starting from the vertical or oft position, the longer arm 03 of the switch 1) being at the top, and moving it in either direction, the field is closed through the whole oi resistance E or F, depending uponthe direction of rotation desired of the motor C. If moved iii-the opposite direction from that shown in the figures, the same circuit connections would have been established, except the resistance 13 would have been used instead of E, and the current through the field b, and consequently the generator voltage, would have been reversed.

Referring now particularly to Fig. 1., if it is desired to stop the rotation of the motor, the control switch is moved backward toward the vertical, cutting more of the resistance E into the field 5, until the whole resistance is cut in, after which the field circuit is broken, and the auxiliary. pole winding short-circuited through the contacts 4 and 5 by means of the switch D, thereby killing the auxiliary or commutatin field. This short-circuit may contain a resistance 6. By moving the switch in a similar manner, in a circuit as shown in Fig. 2, after breaking the field circuit 6, a circuit is made from the exciter B, through the contacts 6 and 7, the winding f, which is also placed on the auxiliary poles, through the contacts 8 and 9, to the other terminal of the exciter. In case the control switch had been in the position for the opposite direction of rotation, a movement of the switch F to the oil position reverses the direction of the current through the winding 7, by means of the contacts 8, 6, 7 and 9. The direction of the current through the second winding f on the auxiliary. poles, creates a magnetomotive force which is opposed to that created by the winding a. Thus the weakening of the auxiliary'pole excitation can be so proportioned that the excitation of the auxiliary poles is annulled.

In Fig. 3 he winding 7" is similar to the winding f in '1 lg. 2, and in the oil position of the switch D, a circuit is made through this. winding 1, the contacts 10 and 11, and through the auxiliary brushes h of the generator. These auxiliary brushes are placed midway between the main brushes. The potential between the auxiliary brushes it reverses with a reversal of the direction of current in the main circuit, and consequently, it not necessary to reverse the connections to toe winding f in Fig. 3. When the control switch is in its oil position and the connections are properly made so as to annul or kill the tendency of the auxiliary field to act a series field, all current supplied to the otor 1s effectively diminished to a ll amo11nt,'and practically to zero, ning the armature circuit.

we claim as new, and desire to seseason cure by Letters Patent of the United States, is,-

1. In combination with a so arately-ex' cited generator having an aurnliai v field and a motor supplied b:" said generator, means for controlling the main field strength of the generator to vary the voltage supplied to said motor, and means for killing said auxiliary field when the main field circuit of the generator is broken.

2.1m combination with a generator having an auxiliary field and a motor supplied by the generator, a separate source of cur rent, and a controlling switch adapted to connect the main field of the generator to said source to vary the amount of current supplied to said main field, and in its oil position to actuate means for killing said auxiliary field when the main field circuit of the generator is broken.

3. In combination with a generator having an auxiliary field winding in series with the armature of said generator, and a motor supplied by said generator, means for controlling the main field strength of the gen orator to vary the voltage supplied to said motor, and means for killing said auxiliary field when the main field circuit of the generator is broken.

4. In combination with a generator having an auxiliary field winding in series with the armature of said generator, of a motor supplied by said generator, means for controlling the main field strength 01 the generator to vary the voltage supplied to said motor, a second auxiliary field winding, and means for supplying said secondauxiliary field winding with current so as to create a magnetomotive force in opposition to that of the first winding.

5. In combination with a generator having an auxiliary field winding in series with the armature of said generator, of a motor supplied by said generator, a separate source of current, a second auxiliary fieldwinding, and a. controlling switch adapted to connect the main field winding of the generator to said source, to vary the amount of current supplied to said main field. winding, and in its off position to connect said second auxiliary field windingwith a source of cur rent so as to create a magnetomotive force in opposition to that of the first winding to prevent said generator from building up as a series machine.

6. In combination with a generator having an auxiliary field winding in series with the armature of said generator, of a motor supplied by said generator, a separate source of current, a second auxiliary field winding, and a controlling switch adapted to connect the main field windin of the generator to said source, to vary tide amount of current supplied to said main field winding, and in its off position to connect said second ceases field strength of the generator to vary the voltage supplied to said motor, a second auxiliary field winding, and means for su pplying said second auxiliary field winding 15 a magnetomotive force in opposition to that with current from said source so as to create;

of the firstwinding to prevent said generator from building up as a series machine.

8. In combination with a generator having an auxiliary field winding in series with the armature of said generator, and a motor sup lied by said generator, means for controlling the main field strength of the generator to vary the voltage supplied to said motor, and means for killing the auxil iary field when the main field circuit of the and in its generator is broken comprisin an opposing and a source winding on said auxiliar fiel of current supplying said opposing winding.

9. In combination Wltllil generator hav ing an auxiliary field winding in series with the armature of said generator, and a motor supplied by said generator, a separate source of current, and a controlling switch adapted to connect the main field winding of the generator to said source to vary the amount of current sup ilied to said main field winding elf position to actuate means for killing said auxiliary field so as to i keep the generator from building up as a se- ,ries machine, said means comprising an opposing winding on the auxiliary field and connections td said separate sdu-rce of current.

In witness whereof, we have hereunto set our hands this twenty-first day of Febrhary 1908i LIONEL FLEISCHMANN. enons STERN.

Witnesses:

RICHARD NEUMANN, Jonann ALEXANDER. 

